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Chapter 18

Classification

S e ction 1 8 – 1 F ind ing O r d e r in D iv e r sity ( p ag e s 4 4 7 – 4 5 0 )

This section explains how living things are organized for study.

W hy Clas s i f y ? (pag e 4 4 7 )

1. W h y d o b io lo g ists u se a c lassif ic atio n sy stem to stu d y th e d iv er sity

o f life?

2 . T h e sc ien c e o f c lassif y in g o r g an isms an d assig n in g th em

u n iv er sally ac c ep ted n ames is k n o w n as .

3 . Is th e f o llo w in g sen ten c e tr u e o r false? I n a g o o d sy stem o fc lassif ic atio n , o r g an isms p lac ed in to a p ar tic u lar g r o u p ar e lesssimilar to eac h o th er th an th ey ar e to o r g an isms in o th er g r o u p s.

A s s i g n i n g S c ien ti f i c N am es (pag e 4 4 8)

4 . W h y is it c o n f u sin g to r efer to o r g an isms b y c o mmo n n ames?

5 . Cir c le th e letter o f eac h sen ten c e th at is tr u e ab o u t ear ly eff o r ts atn amin g o r g an isms.

a. Names w er e u su ally in E n g lish .

b . Names o ften d esc r ib ed d etailed p h y sic al c h ar ac ter istic s o f asp ec ies.

c . Names c o u ld b e v er y lo n g .

d . I t w as d iff ic u lt to stan d ar d iz e th e n ames.

6 . T h e tw o - w o r d n amin g sy stem d ev elo p ed b y L in n aeu s is c alled

.

7 . Cir c le th e letter o f eac h sen ten c e th at is tr u e ab o u t b in o mialn o men c latu r e.

a. T h e sy stem is n o lo n g er in u se to d ay .

b . E ac h sp ec ies is assig n ed a tw o - p ar t sc ien tif ic n ame.

c . T h e sc ien tif ic n ame is alw ay s w r itten in italic s.

d . T h e sec o n d p ar t o f th e sc ien tif ic n ame is c ap italiz ed .

8. W h at is th e g en u s o f th e g r iz z ly b ear, U rsus arctos?

15 0 G u id ed R ead in g an d S tu d y W o r k b o o k / Ch ap ter 1 8

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Grizzly bear Black bear Giant panda Red fox

KINGDOMAnimalia

Chordata

Mammalia

Carnivora

Ursidae

Ursus

SPECIESUrsus arctos

Abertsquirrel

Coralsnake

Seastar

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L innaeu s’s System o f Classificatio n (pages 449 – 450)

9 . A group or level of organization in tax onomy is called a tax onomic

category, or .

10. The largest tax onomic category in Linnaeus’s system of

classification is the , and the smallest is the

.

11. What two kingdoms did Linnaeus name?

12. F ill in the name of each missing tax onomic category in the chartbelow.

Reading Skill Practice

Taking notes can help you identify and remember the most important informationwhen you read. Take notes on Section 18– 1 by writing the main headings and undereach heading listing the most important points. Include in your notes the bold-faced terms and sentences. Do your work on a separate sheet of paper.

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Section 18–2 Modern Evolutionary Classification (pages 451–455)

This section explains how evolutionary relationships are important inclassification. It also describ es how D N A and R N A can help scientistsdetermine evolutionary relationships.

I ntroduction (page 451)

1. What traits did Linnaeus consider when classifying organisms?

P roblems With T raditional Classification (page 451)

2. What problems are faced by taxonomists who rely on body

structure comparisons?

E v olutionary Classification (page 452)

3. Is the following sentence true or false? Darwin’s theory ofevolution changed the way biologists thought about classification.

4. H ow do biologists now group organisms into categories?

5. Is the following sentence true or false? Genera placed within afamily should be less closely related to one another than to

members of any other family.

6. The strategy of grouping organisms together based on their

evolutionary history is called

.

Classification U sing Cladograms (page 453)

7. Circle the letter of each sentence that is true about cladisticanalysis.

a. It considers only traits that are evolutionary innovations.

b. It considers all traits that can be measured.

c. It considers only similarities in body structure.

d. It is a method of evolutionary classification.

8. Characteristics that appear in recent parts of a lineage, but not in

its older members, are called .

Chapter 18, Classification (continued)

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9. A diagram that shows the evolutionary relationships among a

group of organisms is called a(an) .

10. Is the following sentence true or false? Derived characters are

used to construct a cladogram.

Similarities in D NA and R NA (page 454)

11. Is the following sentence true or false? Some organisms do not

have DNA or RNA.

12. How do similarities in genes show that humans and yeasts share

a common ancestry?

M olecular Clock s (page 455)

13. A model that uses DNA comparisons to estimate the length oftime that two species have been evolving independently is known

as a(an) .

14. A molecular clock relies on the repeating process of

.

15. Why are only neutral mutations useful for molecular clocks?

16. Is the following sentence true or false? The degree of dissimilarityin DNA seq uences is an indication of how long ago two species

shared a common ancestor.

17. Why are there many molecular clocks in a genome instead of just

one?

Section 18–3 Kingdoms and Domains (pages 457–46 1)

This section describes the six kingdoms of life as they are now identified. Italso describes the three-domain system of classification.

The Tree of Life Evolves (pages 457–458)

1. Is the following sentence true or false? The scientific view of life

was more complex in Linnaeus’s time.

2. What fundamental traits did Linnaeus use to separate plants from

animals?

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3. What type of organisms were later placed in the kingdom P rotista?

4. M ushrooms, yeast, and molds have been placed in their own

kingdom, which is called .

5. Why did scientists place bacteria in their own kingdom, the M onera?

6. List the two groups into which the M onera have been separated.

a.

b.

7. Complete the concept map.

Chapter 18, Classification (continued)

The Six-kingdomSystem

includesAnimalia Archaebacteria

The Three-Domain System (page 458)

8. A more inclusive category than any other, including the kingdom,

is the .

9. What type of analyses have scientists used to group modern

organisms into domains?

10. List the three domains.

a.

b.

c.

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11. Complete the chart below.

Domain Kingdom Examples

Eubacteria Streptococcus, Escherichia coli

Archaea

Protist

Mushrooms, yeasts

Plantae

Sponges, worms, insects, fishes, mammals

CLASSIFICATION OF LIVING THINGS

Domain B acteria (page 459)

12. Circle the letter of each sentence that is true about members of thedomain B acteria.

a. They are multicellular.

b. They are prokaryotes.

c. They have rigid cell walls.

d. The cell walls contain peptidoglycans.

13. Is the following sentence true or false? All members of the

domain B acteria are parasites.

Domain Archaea (page 459)

14. Circle the letter of each sentence that is true about members of thedomain Archaea.

a. They are unicellular. c. They lack cell walls.

b. They are eukaryotes. d. They lack cell membranes.

15. Is the following sentence true or false? Many members of thedomain Archaea can survive only in the absence of oxygen.

Domain Eukarya (pages 460–461)

16. Circle the letter of each sentence that is true about all themembers of the domain Eukarya.

a. They have a nucleus.

b. They are multicellular.

c. They are heterotrophs.

d. They have cell walls and chloroplasts.

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Match each kingdom with the description that applies to members of thatkingdom.

K ingdom

17. Protista

18. Fungi

19. Plantae

20. Animalia

WordWise

Use the clues to help you identify the vocabulary terms from C hapter 1 8 . Then,put the numbered letters in the right order to spell out the answer to the riddle.

Clues V ocabulary Terms

Most inclusive taxonomic category1

Group of similar families2

Group of closely related classes3

Type of classification based on evolutionary history

4

Group of closely related orders5

Group of closely related species6

Branching diagram showing evolutionary change7 8 9

O ne of two domains of unicellular prokaryotes10

Group of genera that share many characteristics11

Group into which organisms are classified12

The other domain of unicellular prokaryotes13

Domain of all organisms whose cells have nuclei14

Riddle: What kind of clock does a paleontologist use?

Answ er:1 2 3 4 5 6 7 8 9 10 11 12 13 14

Chapter 18, Classification (continued)

Description

a. They have cell walls of chitin.

b. They have no cell walls or chloroplasts.

c. They include slime molds and giant kelp.

d. They include mosses and ferns.